The International Telecommunication Union Standardization Sector (ITU-T) defines an Optical Transport Network (OTN) as a set of Optical Network Elements (ONE) connected by fiber optic links, able to provide functionality of transport, multiplexing, routing, management, supervision and survivability of optical channels carrying client signals. The OTN was designed to provide support for optical networking using wavelength division multiplexing (WDM) unlike its predecessor SONET/SDH.
Typical signals that OTN equipment processes at the Optical Channel layer may include: OTN, SONET/SDH, Ethernet/Fiber Channel, Packets. These signals may undergo the following transformations: Protocol processing of all the signals (such as Forward Error Correction on OTN signals; Multiplexing and de-multiplexing OTN signals; Mapping and de-mapping of non-OTN signals into and out of OTN signals) and Packet processing in conjunction with mapping/de-mapping of packet into and out of OTN signals.
ITU-T G.709 (G.709) provides network interface definitions for the OTN. It defines standard interfaces and rates, improves transport network performance and facilitates the evolution to higher backbone bandwidths. The three parts of the G.709 frame are the overhead, the payload, and the forward error correction (FEC). The overhead provides operation, administration, and maintenance (OAM) capabilities. The FEC helps reduce the number of transmission errors on noisy links, which enables the deployment of longer optical spans.
The current OTN standard does not provide encryption to the payload carried in OTN frames. Thus the end user must rely on high-layer solutions to provide end-to-end encryption.
Therefore, improvements in OTN-related encryption are desirable.